This technology relates generally to sealing fluid flow passages inside flow control devices, such as those particularly suited for use in high pressure oil and gas production and processing systems.
One such type of flow control device is a valve. Generally, a valve forms a flow passage and has a selectively operable closure to open or close the flow passage in order to control a flow of fluid through the valve. The sealing integrity of high pressure valves must withstand not only high operating fluid pressures, presently 15,000 pounds per square inch and higher, but also must do so while controlling the flow of corrosive and/or abrasive fluids that are notorious for eroding the valve internal components in the oil and gas industry. Preferably, the valves can withstand pressures up to at least 22,500 pounds per square inch.
Illustrative embodiments herein are directed to a plug valve although the contemplated embodiments are not so limited. In a plug valve the flow passage typically includes a valve body in fluid communication with two or more openings, typically an inlet opening and an outlet opening, forming a flow passage through the valve body. A valve plug and insert segments, one type of a valve closure that is described herein, are disposed in a valve body bore between the inlet and outlet openings where sealing occurs between the plug, the insert, and the bore. The valve plug defines a through-opening and is selectively rotatable to an open position where the through-opening is aligned with the flow passage to permit a flow of fluid through the valve (from the inlet to the outlet), or to a closed position where the through-opening is misaligned with the flow passage to prevent the flow of fluid through the valve. Operating a valve in the harsh oilfield conditions can cause erosion of the valve body bore where the seal in the insert abrades against the bore, often resulting in leakage in a short amount of time. Repairing the valve body, such as by a weld build-up and machining operation, is a cumbersome and disruptive repair in the oilfield.
The illustrative embodiments of this technology directed to plug valves are in no way limiting of the contemplated embodiments of this technology. The skilled artisan understands that in alternative embodiments this technology can be used in other types of valves having differently configured closures. However, an enumeration of all the different types of valves that are suited for using this technology is not necessary for the skilled artisan to understand the scope of the claimed subject matter, so no such enumeration is warranted.
Besides valves, other types of high-pressure flow devices are also suited for practicing this technology. For example, a fluid end is used in many well servicing applications to contain high pressure, often corrosive and/or abrasive, fracturing fluids in the oil and gas industry. A fluid end typically has a manifold body and a number of components mounted and sealed to the body, such as the suction and discharge plugs, suction and discharge valve seats, stuffing box, discharge flange, and suction manifold; with those components either alone or sleeved as are illustratively described herein. Like the valves, operating a fluid end in the harsh oilfield conditions can cause erosion of the body resulting in leakage in a short amount of time. Repairing the body is also cumbersome and disruptive in the oilfield.
Improvements are needed in the internal sealing of high pressure flow devices to increase operating life while reducing downtime and operating cost. What is needed is a solution that transfers the erosion (corrosion and abrasion) from the high pressure fluid device body to the component sealed with the body. It is to those improvements that embodiments of this technology are directed as described in the illustrative embodiments and contemplated within the scope of the claims.